You may not forget the past but skills and other things will dull over time like if you were a thief as a kid but you stopped doing that for a long time you couldn't just go back to doing it and think you will be just as good. Your skills will have dulled from disuse but it would still be easier to relearn it then to learn it from the begining. This would effect conversation skills also since you will start losing the conversation skills needed to say talk to a peasent.

It is more of a dulling of the skills then forgeting them all together and you would have to relearn them to use them again.